Power driven typewriting machine



Dec. 19, 1933.

R. G. THOMPSON POWER DRIVEN TYPEWRITING MACHINE Filed July 11, 1931 INVENTOR ATTORNEY Patented Dec. 19, 1933 UNITED STATES PATENT OFFICE POWER DRIVEN TYPEWRITING MACHINE Application July 11, 1931. Serial No. 550,156

, 2 Claims.

This invention relates to power driven.typewriting machines, and particularly to machines of that kind comprising a motor or power driven roller for actuating the printing instrumentalities.

The principal object of this invention is the provision of simple and inexpensive means for locking the key levers against actuation when the speed of the power driven roller or its motor is insufficient to actuate the type bars with sufficient force to make a normal impression on the work sheet. v

Another object of the invention is the provision of speed controlled means for locking the key levers against actuation when the motor slows up and releasing them when it again recovers its normal speed.

More specifically, the object of the invention is the provision of a key lock which is automatically moved to ineffective position when the power driven roller acquires normal speed but which is again automatically moved to effective position when the speed of the power driven roller falls below normal.

To these and other ends, the invention consists in the construction and arrangement of parts that will appear from the following description when read in conjunction with the accompanying drawing, the novel features being pointed out in the claims at the end of the specification.

In the drawing:

Fig. 1 is a transverse sectional view of a well known type of power driven typewriting machine, illustrating one possible embodiment of the invention;

Fig. 2 is a sectional detail view taken substantially on line 2-2 of Fig. 1 and looking in the direction of the arrows at said line, and

Fig. 3 is a similar view showing parts in another position.

Referring particularly to the drawing, a power driven typewriting machine of well known form is illustrated, comprising a frame in which a power driven roller 1 is revolubly mounted. Cams, one of which is shown at 2, are arranged to cooperate with the roller 1 for actuating type bars 3, and. means controlled by the usual key levers 4 having keys 5 are provided for operatively connecting the cams with the power driven roller. For convenience of illustration, only one cam 2 and type bar 3 are illustrated, but it will be understood that the usual number are or may be provided. The cam 2 has a projection 6 which is engaged by a spring-pressed arm '7 which tends to turn it into engagement with the power driven roller or a stop 8 on a lever 9 which engages a projection 11 on the cam and normally retains it against actuation. The lever 9 is operatively connected with the key lever so that when the 30 latter is manually actuated it moves the stop 8 from the path of the projection 11 and permits the arm '7 to turn the cam into engagement with the power driven roller. The cam 2 is mounted on one arm of a bell crank lever 12 pivoted at 13 on the frame of the machines and having its other arm 14 operatively connected with a bell crank lever 15 by means of the link 16. The bell crank lever 15 is pivoted on the common pivot rod 17 and is operatively connected with the type bar actuating toggle lever 18 by means of a link 19. The lever 18 is pivoted to the type bar 3 and to a toggle link 21 pivoted on a fixed part 22. When the cam is turned by the power driven roller, the bell crank 12 actuates the bell crank 15, which in turn operates the toggle lever 18 to swing the type bar into engagement with a platen, not shown. A spring 23 connects the bell crank 15 with a fixed part and resiliently retains the parts in normal position with the type 30 bar retracted. A spring 24 connects the key lever with a fixed part and resiliently retains the key leverin elevated position. The parts thus far described are or may be of usual or well known construction, and further detailed description'35 thereof is deemed unnecessary here.

The roller 1 is driven by a motor 25 having a drive shaft 26 which is operatively connected with the shaft 27 on which the roller 1 is mounted. A locking bar 28 is provided for the key levers. Said locking bar extends beneath all the key levers so that when in the locking position shown in Fig. 1, all the key levers 4 may be simultaneously engaged thereby and locked against actuation. The bar 28 is mounted on a shaft 29 pivotally mounted in the frame and has an arm or crank 31 secured thereto at one end, whereby it may be operated from locking position in a vertical plane, as shown in Fig. 1 of the drawing, to a rearwardly inclined or horizontal position out of engagement with the key levers.

Means controlled by the speed of the motor are provided for moving the locking bar from and to locking position. Said means comprises abell crank lever 32 pivoted on a fixed part and having one arm connected with the arm 31 by means of a link 33. The other arm of the bell crank lever 32 is connected with an actuator 34 by means of a link 35. The actuator 34 is so 119 mounted as to be resiliently retained in either of two positions, in one of which the locking bar is in position to lock the key levers and in the other of which it is released therefrom. The opposite sides of the actuator are engaged by resilient members or leaf springs 36 and 3'? which engage notches in opposite sides of the actuator and in opposed fixed members 38 and 39. The resilient members 36 and 37 are flexed to engage their opposite ends with the notches and oppose each other in a manner to support the actuator between them, and are retained therein by virtue of their own resiliency The actuator is guided in its movements by means of a bracket 41 having elongated slots or openings 43 and 44 extending in the same general direction and loosely engaged by studs 45 and/ 46 projecting 'therethrough from the actuator, The studs 45 and 46 may be provided with shoulders, and have threaded ends for the reception of nuts, as shown, which bear against and slidably engage opposite sides of the bracket.

The actuator has a thickened portion 4'? which is engaged by the members 36 and 3'7 and between which and an arm 48 a guideway is formed for a plurality of arms 49 pivoted on a disk 51 secured to the shaft 26 to rotate therewith. The arms 49 are pivoted on the ends of studs 52 projecting from the face of the disk and which serve to space the arms therefrom into the plane of the guideway in the actuator. Each of the arms 49 is pivoted at one end to the stud, and its turning movement thereon is limited by means of a stud 53 projecting therefrom into an arcuate slot 54,.in the disk 51. Contractile coiled springs 55 resiliently connect the studs 53 with the shaft 26.

Briefly the operation is as follows. Assuming the parts to be in the normal position shown in Fig. 1 when the motor is at rest, when the motor is started, the shaft 26 rotates to drive the roller 1, and revolves the disk 51 and the arms 49 mounted thereon. As the speed increases, the free ends of the arms tend to move away from the center of rotation under the action of centrifugal force and against the tension of the springs 55 and engage the upper wall of the guideway in the actuator 34 and tend to move it from the position shown in Fig. 2 to that shown in Fig. 3. The centrifugal force increases with the speed of rotation until it overcomes the resiliency of the springs 36 and 37 and the actuator snaps over the center of greatest contraction into the position shown in Fig. 3. -This movement of the actuator swings the bell crank 32 to pull the link 33 and swings the locking bar 28 from engagement with the key levers, at which time the speed of rotation of the roller 1 is such as to actuate the type bars with sufficient force to make a normal impression on the work sheet. When the speed of the motor slows down from any cause, the springs 55 operate to swing the arms 49 toward the center of rotation and with them the actuator 34 against the resiliency of the springs 36 and 37 until it snaps over the center of greatest retraction and returns the locking bar 28 to locking position. It will be noted that the invention provides means for automatically locking the key levers against actuation whenever the speed of the power driven roller falls below the normal speed required for actuating the type bar to make a normal impression on the work sheet, whether such speed variation results from fluctuations in the speed of the motor or when the motor is stopped or started.

Although only one embodiment of the invention is shown and described herein, it will be understood that this application is intended to cover such changes or modifications as come within the spirit of the invention or scope of the following claims.

I claim:

1. In a typewriting machine. the combination of printing instrumentalities, power driven means for actuating said instrumentalities, keys for controlling the operation of said printing instrumentalities, a locking bar movable to and from locking engagement with said keys, an actuator for said locking bar, resilient means for retaining said actuator in either of two positions corresponding to the position of the locking bar, and means responsive to the speed of said power driven means for moving the actuator against the tension of said resilient means.

2. In a typewriting machine, the combination of printing instrumentalities, power driven means for actuating said instrumentalities, keys for controlling the operation of said printing instrumentalities, a locking bar movable to and from looking engagement with said keys, an actuator operatively connected with said locking bar, resilient means for throwing said actuator to and retaining it in either of two positions corresponding to the position of the locking bar, and centrifugal means controlled by the speed of said power driven means for moving the actuator against the tension ofsaid resilient means.

RUSSELL G. THOMPSON. 

